THIS INVENTION relates to a petrolatum composition.
Petrolatum (petroleum jelly) is a soft, oily, semi-solid mixture of hydrocarbons obtained from high-boiling hydrocarbons and hydrocarbons which are normally liquid at room temperature. Depending on their purity, petrolatums range in colour from dark petrolatum which is impure to highly pure petrolatum which is normally white in colour.
Typical properties of a petrolatum are that it should be a soft unctuous mass and be slightly fluorescent in daylight when molten. A petroleum jelly should be practically insoluble in water, soluble in methylene chloride or hexane, and practically insoluble in alcohol and in glycerol.
Petroleum jellies have a wide range of applications such as pharmaceutical ointment bases, infant care, cosmetics, leather care, elastomers and as a grease or lubricant. Petroleum jelly products are used for human consumption and should therefore be of high purity. For example, the product should contain less than 1 ppm polycyclic aromatic hydrocarbons (which are carcinogenic) and the petroleum jelly should pass acidity/alkalinity and sulphated ash tests.
A white petroleum jelly/petrolatum is a purified and wholly or nearly decolourised mixture of semi-solid hydrocarbons (CnH2n+2), obtained from petroleum and high-boiling liquid hydrocarbons. It should have a white, or almost white, translucent appearance.
Petrolatums are conventionally produced by blending petroleum derived oil components with slack waxes. Slack waxes are obtained during a de-waxing process of lubricant base-oils from crude oil. Such petroleum based petrolatums are described in U.S. Pat. Nos. 2,828,248 and 1,791,926.
Although the term ‘petrolatum’ originates from petroleum, which is a fossil fuel derived product, petrolatum also includes those types which are derived from synthetic sources, being those of which the molecules of at least one component (or all of its components) were derived by chemical synthesis. Petrolatum may also contain natural components such as vegetable waxes.
GB 955348 suggests a blend of 10-30% of Fischer-Tropsch wax with 35-45% petroleum and 35-45% of liquid polypropylene, for use as a cable impregnant. JP 2009-234991 describes the use of a Fischer-Tropsch wax and a liquid paraffin to provide a stick cosmetic. The properties of a stick cosmetic are however very different to that of a petrolatum in that a stick cosmetic is not an unctuous paste, which a petrolatum is. Instead, a stick cosmetic is more solid and harder than a petrolatum because it needs mould release properties.
The use of synthetic components in petrolatum has been suggested in U.S. Pat. Nos. 7,851,663, 3,764 and JP 2009-234991. U.S. Pat. No. 7,851,663 teaches the grafting of long chain olefins and paraffins produced by Fischer Tropsch synthesis, to yield iso-paraffins with long-chain branching exhibiting properties of petrolatum.
Synthetic waxes, eg. those obtained from the Fischer-Tropsch process, do not contain significant amounts of aromatic and polynuclear aromatic components, which is beneficial for petrolatum. However, when synthetic components are used in a petrolatum formulation, obtaining the desired stability and three-dimensional network structure of the petrolatum remains a challenge. In particular, when a petrolatum composition contains a linear paraffin which is liquid at room temperature, the linear paraffin tends to separate from the heavier components in the formulation leading to a non-stable petrolatum formulation. In order to obtain a stable composition a “solvent binding” effect is required.
It is an object of this invention to provide a stable petrolatum containing normally liquid linear paraffins.